The present invention refers to an accelerated walkway for conveying passengers or materials, which provides major improvements in the ease of use, in its requirements for space necessary for implementation and in the simplicity of its mechanisms.
Different systems are already known for obtaining variable speed walkways intended for conveying passengers or materials, among which can be mentioned, as the most important, the following:
1. Variable speed walkway consisting of various rubber bands which are turned at constant speed. The rubber bands at the extremities turn at a slower speed, and the rubber band in the centre turns at a higher speed, whereby a slow speed is achieved at the entrance and at the exit. Walkways with such characteristics are described in the patents EP 0854108 A-1, EP 0850870 A-1 and EP 00773,182 A-2.
2. Variable speed walkway consisting of telescopic treadboards. In this solution the variation in speed is achieved by separating some conveyor treadboards from others. The gap that would be produced is covered by some plates which initially are hidden below the surface of the adjacent treadboard. A walkway with these characteristics is described in the patent GB 2264686 A.
3. Variable speed walkway consisting of parallelepipedal treadboards which are displaced laterally with respect to each other. The variation in speed is achieved by changing the direction of movement, maintaining the projection of the velocity constant over the entrance and exit direction. This walkway has a characteristic S-shape. Walkways with these characteristics are described in the U.S. Pat. No. 5,571,254 and in the EP 0646538 A2.
4. Variable speed walkway constituted by a set of interconnected motor-driven grooved rollers. The rollers are of reduced diameter, achieving in this way that the working surface is approximately flat. The variation in speed is achieved by making some rollers turn faster than others. In a variation of this walkway these roller are employed only in accelerating and retarding portions. The portions of constant speed are implemented by means of rubber bands similar to those presently used for conveying passengers, as is described in the FR 2747664 A1.
5. Variable speed walkway consisting of a deformable rubber band. This endless band would be capable of elongation in the centre portion and of widening for entrance and exit, thereby achieving the variation in speed, as is described in the EP 0831052 A1.
6. Variable speed walkway consisting of an endless worm of overlapping treadboards. The variation in speed is achieved by the displacement of some treadboards with respect to others, as is described in the GB 2025872.
The walkway of the invention is made up of sets of treadboards of variable length which are mounted on lateral traction chains, with which is related a drive mechanism, in a form similar to that of system 6 described above.
Compared with these systems the walkway of the invention is characterised in that each set of treadboards comprises a front and rear treadboard, slotted and mutually articulated along an axis perpendicular to the direction of movement.
Of the two treadboards that make up each set of treadboards, the rear treadboard is mounted on the lateral traction chains and also on lateral guidance rails. For its part, the front treadboard rests on and can be displaced over the rear treadboard corresponding to the set of treadboards which is situated immediately in front, by means of guide elements.
According to another characteristic of the invention, each of the side chains is constituted on a basis of links consecutively articulated to each other through their extremities. The links in the chains can all have an elbowed shape or include elbowed links and straight links. In any case one of the straight spans of the elbowed links is articulated at its extremities with the adjacent links, be they straight or elbowed.
The chains mentioned run between lateral guides that cause the links, be they straight or elbowed, to swivel between a folded position, in which the length of the chain is reduced, resulting in the partial overlaying of the treadboards that form the walkway, and a maximum extension position, in which the chain reaches its maximum length and produces the positioning of the treadboards in coplanar alignment. It is in this position of maximum extension that the links can come to be in alignment with the span of elbowed links with which they are articulated.
The swivelling of the links takes place in a progressive manner between the centre span of the chains and the outermost spans thereof, whereby a variation in speed is achieved of the displacement on the surface defined by the treadboards, this speed being maximum in the centre span and minimum in the outermost spans. In the outermost span an acceleration and retardation occur in correspondence with the start or the entrance portion and the end or the exit portion of the chain, respectively.
The walkway is completed with drive equipment or elements for the two chains that carry in traction the treadboards, a supporting frame, two side balustrades similar to those of conventional constant speed walkways, handrails, fixed treadboards in the entrance and exit portions and the electrical and safety components and elements necessary for the correct operation of the walkway, all of which have a constitution and disposition which are known.
In each treadboard assembly, the rear treadboard is fitted on each of its sides with longitudinal guides, with two rear coaxial rollers that form part of the lateral traction chains, and with front coaxial rollers which can move over the side guidance elements. The front treadboard, of each set of treadboards, has for its part on each of the sides, front coaxial sliding or rolling elements, which can move over the guides of the rear treadboard corresponding to the set of treadboards situated immediately in front.
The support of the chains of the side guidance elements is produced through the elbowed links, by means of rolling elements with axle perpendicular to the link. These rolling elements shall preferentially coincide with articulations between the links of the chain.
The two treadboards of each set of treadboards have complementary adjacent edges which are coupled to each other in the coplanar position of these treadboards.
In the centre portion of the walkway, where the chains run in the maximum extension position, the treadboards of the different sets occupy coplanar positions. In the outermost portions, where the chains run in the position of maximum folding, the rear treadboards of the different sets run under the front treadboards, these front treadboards being in a horizontal position, with the adjacent edges coupled to each other. In any of the positions described, the axle of the rolling or sliding elements of these front treadboards coincides with the line of intersection of the parallel planes equidistant from the respective walking surfaces of the front sub-treadboard and the adjacent rear one.
When the transition occurs between portions of maximum extension and portions of maximum folding of the chain, the overlapping between front and rear treadboards varies progressively, the front treadboards being maintained in a noticeably horizontal position and the rear treadboards at a slight inclination, in opposition to the direction of movement.
In the entrance and exit portions, the front treadboards of the sets of treadboards move in a coplanar and aligned manner, the transition with the fixed surface of the walkway occurring by means of a system of combs.
The traction chains can be engaged at their outermost points with auxiliary pinions or chains that maintain the distance between the links and also facilitate the tilting of the treadboards between the forward-going and backward-going segment of the assembly. At least one of these auxiliary pinions or chains can be in relation with the drive mechanism.